This invention relates to an electric double layer capacitor and manufacturing method thereof, and more preferably to polarizable electrodes of the electric double layer capacitor and manufacturing method thereof.
A cross sectional view of a fundamental element of a conventional electric double layer capacitor (hereinafter referred to as a fundamental cell) is shown in FIG. 1. The construction of the fundamental cell is formed to impregnate electrolytic solution into activated carbon powder as the polarizable electrodes 8, to face a couple of the polarizable electrodes 8 each other through the electron insulating and ionic permeable porous separator 4, and to hold the polarizable electrodes 8 and electrolytic solution with collectors 2a and a gasket 5. In this conventional electric double layer capacitor, the fundamental cells are connected in series corresponding to the required breakdown voltage because the voltage resistance of this fundamental cell is controlled by the electrolysis voltage of electrolytic solution. The conventional electric double layer capacitor is restrictedly used mainly for backup power supply of memories, IC or the like as a counter measure against instantaneous power disconnection, because its equivalent-series resistance is which as more than hundreds m.OMEGA..
However, when it is used for an auxiliary power supply for energy to drive a motor, the equivalent series resistance must be small. Also in case of using for supplying backup power, the one of which whole height is low is required.
A activated carbon/polyacene material and an electric double layer capacitor that uses it as a material, which are shown in Japanese Patent Application No. 2-266498 and Japanese Patent Application No. 2-266499, have a possibility to meet these requirements. In the electric double layer capacitor shown in Japanese Patent Application No. 2-266499, conductive substrates or conductive sheets are used as a substrate material, and forming thick film electrodes made of composite material of activated carbon/polyacene on the substrates, these are used as polarizable electrodes.
In this case, however, conductive substrates or conductive sheets are used as substrate materials, so that in case of connecting fundamental cells in series for rising breakdown voltage the height of the capacitor can not be lower because the fundamental cells are layer built. Also, there is another defect that serially connected fundamental cells can not be made all at once.
Moreover, on the electric double layer capacitor utilizing conductive substrates or conductive sheets are as substrate materials, a plurality of electrically insulated polarizable electrodes of the electric double layer capacitor can not be made on the same substrate. Therefore, the conventional art has a defect that a plurality of electric double layer capacitors arranged as sharing the same substrate can not be made on the same plane.